The aim of this protocol is to obtain pulmonary and nutritional information on infants with Cystic Fibrosis (CF) identified through the newborn screen. This protocol continues to thrive with approximately 18 new patients added each year. This past year we began studies of Pseudomonas antibodies and CA-19,9 - a potential biomarker of mucous accumulation. The current studies have continued to identify early abnormalities in infants with CF, and they also provide information on surrogate markers of outcome.